This is quite serious, and if it plays out, its the Turkish PM trying his best to play the part of Archduke Franz Ferdinand.
It is serious, but it is important to note that this is not (at least not yet) the official position of the Israeli government.
However, it is not insignificant that the former #2 IDF officer is putting this out there on the record. Wouldn’t suprise me to see more and more of the Israeli right pushing Bibi to take this position.